Combine sugar and water in a saucepan. Bring to a boil, then simmer for 8 minutes. Add lemon juice, simmer 2 minutes, remove from heat, and stir in orange blossom water. Cool completely.
If the akkawi is salty, soak it in cold water for 30 minutes, changing the water once. Drain, pat dry, and shred.
Assemble:
Heat the oven to 375°F (190°C). Cut the kataifi into short strands and toss thoroughly with melted clarified butter.
Press two-thirds of the pastry firmly across the base and slightly up the sides of the pan. Spread cheese evenly, leaving a narrow border.
Cover with the remaining pastry and press gently into an even layer.
Bake and Syrup:
Bake for 30 to 35 minutes, until deeply golden and crisp.
Immediately pour about three-quarters of the cool syrup evenly over the hot kunefe. Rest 5 minutes, garnish with pistachios, and serve with extra syrup alongside.
Notes
Low-moisture mozzarella can replace akkawi, though the flavor will be milder.
Use clarified butter rather than whole butter to keep the pastry crisp and prevent burnt milk solids.